Invasive Plant Medicine

What is an invasive species?

Invasive species are non-native and spread aggressively in the environment and negatively impact the health and/or survival of native species. What species are defined as invasive can vary by region. In general, invasive species rapidly colonize an environment and disturb or negatively altar local ecosystems. Some examples of invasive species are Japanese Barberry (Berberis thunbergii), Multiflora Rose (Rosa multiflora), Garlic Mustard (Alliaria petiolata), and Japanese Knotweed (Fallopia japonica).

Invasive species are different from naturalized species or species with an invasive growing habit.

Naturalized species are non-native, but co-exist with native species. While some are considered weeds, like Dandelions (Taraxacum officinale), they are not classified as invasive because they do not completely overtake the environments they grow in or prevent native species from thriving.

Plants with invasive growing habits may be native or non-native. These plants are prolific spreaders and can quickly take over garden beds and fields. However, native species with invasive growing habits have natural predators to keep their growth in check and they often grow alongside other species. Additionally, many of these species are easier to control than plants listed as invasive species. Plants with invasive habits generally grow in colonies, like Goldenrod (Solidago spp.) and Raspberry (Rubus idaeus).

Harvesting for Medicine and Invasive Species Control

We can help to manage invasive species through careful harvesting practices. For some species, continual harvesting weakens the plant’s energy reserves, which eventually leads to decline. Non-chemical management plans for plants like Multiflora Rose and Japanese Knotweed recommend periodic cutting throughout the growing season to weaken the plants and reduce their growth in subsequent years. Harvesting roots and stems are one way to help manage invasive species populations. There are some basic rules to follow when harvesting invasive species for medicinal use.

  1. Be mindful of herbicides
    Invasive species are commonly sprayed on public lands, including parks. Glyphosate is one of the most commonly used herbicides to control Japanese Knotweed and other invasives. For woody species, the chemical may be injected directly into the stems. Areas where plants have wide-spread wilting or browning should always be avoided. If you aren’t sure if an area has been sprayed, contact your local parks department or public works. Or simply err on the side of caution and don’t harvest from areas that may be sprayed.

  2. Look for safe harvesting locations
    Never, ever harvest from roadsides, railways, near powerlines, or industrial areas (former or current). These areas tend to have high levels of contaminants including herbicides, heavy metals, and petroleum runoff. This is especially problematic for harvesting roots which can accumulate toxins.

  3. Don’t help them spread
    Once you’ve found a safe place to harvest, be careful not to help the plants in expanding their colony. Harvest plant material in bags without openings, to prevent root or stem pieces from falling out. If you dig or pull more plants than you can use, don’t leave plant material on the ground. Hang roots from tree branches so they will dry out and die. Be sure to inspect your shoes for roots, seeds, or other plant materials trying to hitch a ride. Plants like Japanese Barberry have extremely high seed germination rates, so a single seed can lead to a new potential colony. Japanese Knotweed has low seed germination rates, but can easily reproduce from leaves, stems, and root pieces (even small ones).

  4. Don’t let them take root at your home
    It may be tempting to have your own patch of guaranteed herbicide free Japanese Knotweed or Garlic Mustard on your land, but please don’t succumb to this temptation. These invasive plants do not play nicely with others and will quickly overtake your garden or yard. Not to mention planting invasive species is illegal in many areas. Once these plants are established, constant management is required for at least 5 to 10 years, if not indefinitely. Many people already have at least one of these species on their property, however. If they’re not growing in your yard, perhaps a neighbor has them who would be happy to let you harvest some invasive plants. Finally, never ever put plant material from these species into your compost bin or brush piles!! They will survive and come back to haunt you and your garden.

Check out my wildcrafting and wild gardening posts for more!

Medicinal Invasive Species in New England

New England has many notorious invaders that threaten local ecosystems, outcompete native plants, and even threaten human health. The good news is, some of the most difficult to manage species are also highly medicinal! This is an overview of some commonly encountered medicinal invasives.

Japanese Barberry (Berberis thunbergii)

About: Native to Asia, Japanese Barberry is a highly invasive shrub across the North East. The plant thrives in full sun as well as in shaded forests and often forms dense stands. One of the major health concerns with Japanese Barberry is its relationship to Lyme disease. The plant’s dense and thorny canopy provides an ideal habitat for the White-footed Mouse, which is a vector of Deer Ticks. Additionally, ticks thrive in the shrub’s dense foliage, which creates the high humidity environment they favor. Harvesting this plant can help keep its populations under control, which may reduce habitat favorable for ticks.

Description: Small deciduous perennial shrub growing 2 to 8 ft tall. Branches are covered in long, thin, straight spines. The leaves are small and paddle shaped. Flowers are pale-yellow to white in drooping clusters from mid-spring to early-summer. Bright red tear-drop shaped berries develop in fall and persist through mid-winter. The root is bright yellow.

Parts Used: Root, Bark, Berries

Alternative to: Oregon Grape (Mahonia aquifolium), Goldenseal (Hydrastis canadensis), and Goldthread (Coptis trifolia)

Energetics: Bitter, dry, warm

Actions: Lymphatic, anti-microbial, antioxidant, cholagogue, cardioprotective, diaphoretic, astringent, anti-inflammatory, digestive, antiseptic, diuretic

Medicinal Uses: Japanese Barberry is a powerful ally to the lymphatic system, immune system, biliary system, and urinary tract. The yellow root contains Berberine, the same alkaloid found in the at-risk species Oregon Grape, Goldenseal, and Goldthread. Because of this, Japanese Barberry is a good substitute that can help reduce harvesting pressures on our native at-risk medicinals. Berberine is the constituent behind many of Japanese Barberry’s actions. This plant is particularly useful in addressing bacterial infections and digestive issues. As a lymphatic and cardioprotective herb, Japanese Barberry helps keep the body’s fluids moving and strengthens the heart by increasing contractility. Some issues that Japanese Barberry can help with are: Urinary infection, Liver infection, Low bile production, Slow digestion, Constipation, Diarrhea, Fever, Candida, Lyme’s disease, Psoriasis, Eczema, Acne, Diabetes, Weight, Inflammatory pain, GI inflammation. Japanese Barberry also helps to increase white blood cell count and assists the immune system to make it more effective in attacking mutated cells. The berries are blood building as well, when made into a tincture or decoction.

Dosing & Preparation: Japanese Barberry is a low to moderate dose herb that should not be used for extended periods of time. Do not use for more than a week at a time. Take a break of at least 3 weeks before starting again.

  • Tincture: 1 to 30 drops up to 3x per day
  • Tea: 2-3 tsp dried root or berries decocted in 8 oz of water taken up to 3x per day
  • Topical wash: 1-2 Tbs of dried root decocted in 16 oz of water

Harvesting: Roots are best to harvest in Spring and Fall. Berries are ripe Fall through Winter

Combines well with: Mullein, Coltsfoot, Wild Cherry, Elderberry

Precautions: Large doses are purgative. Not to be used during pregnancy

Japanese Knotweed (Fallopia japonica)

About: Native to Asia, Japanese Knotweed is an extremely invasive plant in the Buckwheat family. It is commonly found in disturbed habitats and along streambanks where it rapidly creates a dense monoculture. It grows in full sun to part shade. Japanese Knotweed stands outcompete other species and create such intensely shaded understories that other plants struggle to survive. The plant is difficult to eradicate due to its ability to lie dormant for years, rapid growth, and extensive root systems. It can grow up to 10 feet per month, has roots that reach down over 10 feet into the Earth, and can grow through concrete and even home foundations. The plant is also able to reproduce from sections of stem, leaves, or roots as well as via seed (though germination rates are low due to most plants being female). On a positive note, bees seem to love their flowers.

Description: An upright perennial shrub with large, broad leaves and bamboo-like stems. The stems are green with reddish flecks. Red coloring is especially noticeable at stem nodes. The leaves are large and heart shaped with a pointed tip. In the Spring, Japanese Knotweed shoots resemble Asparagus with a reddish-purple color. Flowers are minute and white on plume-like sprays that bloom in late-Summer. The root is orange.

Parts Used: Root, Stem (edible)

Alternative to: Rhubarb (Rheum rhabarbarum) (edible)

Energetics: Moist, sour, cool

Actions: antioxidant, antiviral, antitussive, capillary stimulant, diuretic, immunomodulator, immunostimulant, anti-inflammatory, cardioprotective, antibacterial, anticoagulant

Medicinal Uses: Japanese Knotweed is a medicinal powerhouse! With incredibly high amounts of resveratrol (also found in red grape skins), Japanese Knotweed contains potent antioxidants that are especially beneficial to the heart. Japanese Knotweed’s constituents are able to pass through the blood-brain barrier, imparting some of its actions on the nervous system. This attribute, along with the plant’s antiviral and immunomodulating properties make it particularly useful in managing Lyme’s disease. Additionally, the plant is a capillary stimulant, which helps to increase blood flow to areas where Lyme spirochetes tend to “hide." Japanese Knotweed is also helpful for: maintaining healthy blood vessels, acting as an anticoagulant, modulating and stimulating the immune system, reducing inflammation, soothing coughs, and helping the body to deal with cell mutations.

Edible Uses: The young shoots of Japanese Knotweed can be harvested in early Spring for use as a cooked vegetable. Its flavor is somewhere between Asparagus and Rhubarb. In savory dishes, the shoots can be cooked in butter just like asparagus. Because the shoots are already somewhat sour, you don’t have to add lemon for flavoring. In sweet dishes, cook shoots like rhubarb, adding them to strawberry pies or fruit crumbles. Remove the leaves before cooking and chop or slice the stems.

Dosing & Preparation: Japanese Knotweed is potent but gentle medicine. It can be used long term. When preparing the plant to eat or use for medicine, dispose of unused parts in the garbage or dry them out to burn. Never compost this plant or throw it in a brush pile! It will regenerate!

  • Tincture: 15 to 30 drops up to 3x per day
  • Tea: 1 Tbs dried root in 16 oz of water taken up to 3x per day
  • The root can also be dried, powdered, and encapsulated (best for Lyme treatment)

Harvesting: Roots are best to harvest in Spring and Fall. Shoots in early Spring.
Combines well with: Barberry, Calendula, Astragalus, Elderberry

Precautions: None known

Multiflora Rose (Rose multiflora)

About: Native to Asia, Multiflora Rose is a common sight in much of New England growing along forest margins, the edges of agricultural land, and in fallow fields. It grows in a wide range of environments, but seems to thrive in disturbed soils in full sun to part shade. It forms dense and impenetrable thickets that crowd out native vegetation. Birds, rabbits, and rodents use the plant for shelter and birds love to eat the hips. However, this helps to spread Multiflora Rose’s seeds. This plant also spreads by root sprouts and stems that root upon touching the ground.

Description: A large perennial shrub with arching stems that can grow up to 15 feet tall. The leaves are pinnately compound with serrated leaflets. The stems are covered in numerous thorns, some of which are as small as a needle point. In May and June the plant produces a multitude of white, five petal flowers. These flowers give way to small rose hips that ripen to a bright red in late Summer and persist through early Winter.

Parts Used: Flowers with leaves, hips

Alternative to: Any rose species (Rosa spp.)

Energetics: dry, sour, cool

Actions: antioxidant, anti-inflammatory, nervine, astringent, cardiovascular tonic, aphrodisiac, blood mover, blood tonic, laxative, and styptic.

Medicinal Uses: Multiflora Rose can be used similarly to other rose species, both wild and cultivated. Rose is commonly recommended as a heart medicine, both physically and emotionally. Physically Rose promotes circulation and lowers blood pressure. Emotionally, Rose acts as a nervine to calm anxiety and help relieve symptoms of depression and grief. Similarly, Rose can help people to relax before sex, helping to improve sexual function. It also mildly boosts libido and pairs well with other aphrodisiac herbs. As a blood mover, Rose also helps reduce pelvic congestion that can cause irregular menstruation. Other issues Rose is helpful with include: constipation (with excess mucous), diarrhea, to tone skin, to cool burns and minor wounds, and arthritic inflammation. The hips are especially helpful for colds due to their high vitamin C content.

Dosing & Preparation: Rose can be used long term as needed. Those with very dry constitutions should use Rose moderately or in formula with moistening herbs.

  • Tincture: 15 to 30 drops up to 3x per day
  • Tea:
    • 2 tsp flower/leaf in 8 oz of water taken up to 3x per day
    • 1 Tbs hips decocted in 16 oz of water up to 3x per day
  • The hips can also be made into syrups and jams (strain out seeds)

Harvesting: Flower/leaves in Spring to early Summer. Berries when ripe in late Summer to early Fall

Combines well with: Hibiscus, Peppermint, Hawthorn, Elderberry, Lemonbalm, Shatavari, Damiana, Cocoa

Precautions: Large quantities of Multiflora Rose hips can act as a laxative. The seeds are toxic and should be discarded in the garbage (do not compost).

Purple Loosestrife (Lythrum salicaria)

About: Native to Asia and Europe, Purple Loosestrife is a wetland perennial that grows in clumps. It can form large colonies in wetlands and wet meadows where it outcompetes native plants. Bees use the plant as forage.

Description: An herbaceous perennial that grows from 2 to 4 feet tall. Purple Loosestrife has lance-shaped leaves that grow in opposite or wholed patterns around the stem. In late Summer and early Fall the plant produces showy magenta flowers on a tall spike. The plant prefers moist soils in full sun.

Parts Used: Flowering tops

Alternative to: Eyebright (Euphrasia officinalis)

Energetics: cool, dry, moist

Actions: astringent (toning), mucilaginous, anti-inflammatory, antitussive, antibacterial, hypoglycemic, liver protectant, antispasmodic

Medicinal Uses: Purple Loosestrife is a wonderful antibacterial and anti-inflammatory herb. It acts as an astringent to tone tissue while mucilage in the plant moistens and lubricates. These qualities make the plant especially useful in addressing digestive issues such as IBS, constipation, and diarrhea. The two seemingly contradictory properties of dry and moist work synergistically to balance the body. Purple Loosestrife is a wonderful alternative to Eyebright for soothing sore and dry eyes. As an antibacterial, the plant is very helpful in addressing candida both internally and externally. Purple Loosestrife is also useful for: diabetes (reduces blood sugar), eczema, liver wellness, sore throat, ulcers, and vaginosis.

Dosing & Preparation: Purple Loosestrife is fairly gentle and can be used for extended periods as needed.

  • Tincture: 40 to 60 drops up to 4x per day
  • Tea: 2 tsp flower/leaf in 8 oz of water taken up to 4x per day
  • Eye Wash: make a strong tea. Filter through a coffee filter and let cool. Apply to eyes with a dropper, washing cup, or as a compress.

Harvesting: Summer to early Fall

Combines well with: Plantain, Marshmallow, Calendula, Chamomile
Precautions: Be cautious where you harvest this plant. It is capable of tolerating high levels of lead and may accumulate heavy metals as well as other toxins from the environment. Never harvest from areas that receive runoff from roadways, railways, or industrial areas.

Garlic Mustard (Alliaria petiolata)

About: Native to Europe, Garlic Mustard has become common throughout much of the US. This plant is nearly impossible to eradicate once established due to its prolific seeding. Each plant produces up to 500 tiny seeds. This plant outcompetes other plants by remaining green later into the Winter and coming up early in Spring. It also produces allelochemicals that prevent other plants from growing nearby. It often grows on forest margins and in disturbed soils.

Description: An herbaceous biennial that prefers part sun to shade. First year plants grow as a rosette close to the ground. Second year plants grow up to 3 feet tall and send up a flower stalk that produces a cluster of small white flowers with four petals. The leaves are bright green, spade shaped, and coarsely toothed. When crushed the leaves smell like garlic.

Parts Used: Tops and roots

Alternative to: Ramps (Allium tricoccum) and Horseradish (root)

Energetics: pungent, bitter, cooling, warming

Actions: antiseptic, diaphoretic, circulatory stimulant, digestive bitter

Medicinal Uses: Like other mustards, Garlic Mustard is warming in the sense that it helps to get things moving. As a circulatory stimulant, it helps to improve circulation throughout the body. This can be helpful during illness as well as in Spring, when we need to do some internal “spring cleaning” by getting our blood and lymph moving after Winter sluggishness. Garlic Mustard also has a bitter flavor to it, which increases as the leaves age. This too helps to get fluids (bile) moving, which promotes good digestion. The plant also has antiseptic properties making it useful in addressing external and internal ulcers and sores.

Edible Uses: The best way to make use of Garlic Mustard’s medicine is through food! With its spicy, pungent flavor, it makes at excellent pesto. The flavor is very similar to garlic scapes with a bit of a mustardy bite. The dried leaves can also be added to seasoning mixes for savory dishes. The root can be harvested and used like horseradish. The entire top of the plant can be sautéed and leaves can be eaten raw in salads.

Dosing & Preparation: Garlic mustard is best used in food or added to medicinal vinegars like Fire Cider. Use Garlic Mustard fresh, cooked, dried, or infused into oils/vinegars.

Harvesting: Spring

Combines well with: Nettles (pesto)

Precautions: Never compost this plant! Take care to harvest before the plants go to seed to avoid spreading seeds.

About the author: 

Vincent Frano is an avid student of nature. He is trained as an herbalist with over 10 years of experience in European traditions with knowledge of Ayurvedic and North American herbs. He holds a BS in Sustainable Horticulture from the University of Massachusetts, Amherst where he focused on herbal medicines, native plants, invasive species, and ecosystem restoration. Vincent is the co-founder of Small Victories and is the lead illustrator for Small Victories' products.

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Information on this website has not been evaluated by the U.S. Food and Drug Administration. All information is for educational purposes only. The U.S. FDA does not evaluate or test herbs or herbal products. These products are not intended to diagnose, treat, cure, or prevent any illness or disease. Please consult with your physician for diagnosis or treatment.